4.一对多单向关联(班级对学生):测试

package com.bjpowernode.hibernate;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import org.hibernate.Session;

import junit.framework.TestCase;

public class One2ManyTest extends TestCase {

public void testSave1() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
Student student1 = new Student();
student1.setName("张三");

Student student2 = new Student();
student2.setName("李四");

Classes classes = new Classes();
classes.setName("动力节点");

Set students = new HashSet();
students.add(student1);
students.add(student2);
classes.setStudents(students);

//抛出TransientObjectException
//因为Student不是Persistent状态的对象,它是Transient状态的对象
session.save(classes);
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}

public void testSave2() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
Student student1 = new Student();
student1.setName("张三");
session.save(student1);

Student student2 = new Student();
student2.setName("李四");
session.save(student2);

Classes classes = new Classes();
classes.setName("动力节点");

Set students = new HashSet();
students.add(student1);
students.add(student2);
classes.setStudents(students);

//可以成功保存数据
//但是会发出多余的update语句来维持关系
session.save(classes);
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}

public void testLoad1() {
Session session = null;
try {
session = HibernateUtils.getSession();
session.beginTransaction();
Classes classes = (Classes)session.load(Classes.class, 2);
System.out.println("classes.name=" + classes.getName());
Set students = classes.getStudents();
for (Iterator iter=students.iterator(); iter.hasNext();) {
Student student = (Student)iter.next();
System.out.println("student.name=" +student.getName());
}
session.getTransaction().commit();
}catch(Exception e) {
e.printStackTrace();
session.getTransaction().rollback();
}finally {
HibernateUtils.closeSession(session);
}
}
}